Textile-like patterned nonwoven fabrics and their production



Dec. 23, 1969 F. J. EVANS 3,485,706

TEXTILE-LIKE} PATTERNED NONWO VEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 17 Sheets-Sheet l INVENTOR FRANKLIN JAMES EVANS MaTMM ATTORNEY F. J. EVANS Dec. 23, 1969 TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION 17 Sheets-Sheet 2 Filed Jan. 18, 1968 ATTORNEY Doc. 23, 1969 F. J. EVANS 3,485,706

TEXTILELIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 17 Sheets-Sheet :5

FRANKLIN JAMES EVANS 7410? ZMZWLM A TT WU Y F. J. EVANS 3,485,706

TEXTILE-LIKE PATTERNED NONWOVEIN FABRICS AND THEIR PRODUCTION Dec. 23, 1969 1'? Sheets-Sheet 4 Filed Jan. 18, 1968 H C W I.\"E.\'T( )A FRANKLIN JAMES EVANS Dec. 23, 1969 F. J. EVANS 3,485,706

TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 17 Sheets-Sheet 5 F|G.7 I6. :0

INVENTOR FRANKLIN JAMES EVANS BY WMZW ATTORNFY Dec. 23, 1969 F. J. EVANS 3,485,706

TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 1'7 Sheets-$heet 6 FIG/4 FRANKLIN JAMES EVANS F. J. EVANS Dec. 23, 1969 TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION l7 Sheets-Sheet 7 Filed Jan. 18, 1968 F/G /6G I.\\'E.\'H Ht JAMES EVANS F RANKLIN F. J. EVANS Dec. 23, 1969 TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION 1'7 Sheets-Sheet 8 Filed Jan. 18, 1968 0.05 INCH 0.4 INCH INVENTUR F RAN KLIN JAMES EVANS 7/MZQZWLMW F. J. EVANS Dec. 23, 1969 TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION 1'7 Sheets-Sheet 9 Filed Jan. 18, 1968 F/G 2U F/GZ/ J\\ E\ R)! FRANKLIN JAMES EVANS Dec. 23, 1969 EVANS 3,485,706

TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 17 Sheets-Sheet 10 L INVEXU )R FRANKLIN JAMES EVANS Dec. 23, 1969 F EVANS 3,485,706

TEXTILELIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 1''! Sheets-Sheet 11 F1628 FIG.280

INVEXTUR FRANKLIN JAMES EVANS F. J. EVANS Dec. 23, 1969 TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION 17 Sheets-Sheet 12 Filed Jan. 18, 1968 04 INCH ATTORXFY Dec. 23, 1969 F. J. EVANS 3,485,706

TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 17 Sheets-Sheet 15 FIGESI FIG. 5m

INVENTORS FRANKL'N JAMES EVANS ATTORNEY Dec. 23, 1969 F. J. EVANS 3,485,706

TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 1'? Sheets-Sheet 14 0.005 INCH INVENTOR FRANKUN JAMES EVANS 005 INCH F. J. EVANS Dec. 23, 1969 TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION l7 Sheets-Sheet 15 Filed Jan. 18, 1968 INVENTOR FRANKLIN JAMES EVANS ATTORNEY Dec. 23, 1969 F. J. EVANS 3,485,70

TEXTILE-LIKE PATTERNED ONWOVEN FABRICS AND THEIR PRODUCTION Filed Jan. 18, 1968 17 Sheets-Sheet 16 WINDUP JET TREATING LAYER FORMING INVENTOR FRANKLIN JAMES EVANS FIBER CONBING ATTORNEY STOCK OPENING F. J. EVANS Dec. 23, 1969 TEXTILE-LIKE PATTERNED NONWOVEN FABRICS AND THEIR PRODUCTION 17 Sheets-Sheet 17 Filed Jan. 18. 1968 FIG.4|

F I G. 42

, INVENTOR FRANKLIN JAMES EVANS ATTORNEY United States Patent 3,485,706 TEXTILE-LIKE PA'II'ERNED NONWOVEN FABRICS AND THEIR PRODUCTION Franklin James Evans, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Continuation-impart of applications Ser. No. 299,805, Aug. 5, 1963, Ser. No. 391,641, Aug. 24, 1964, Ser. No. 442,251, Mar. 24, 1965, Ser. No. 462,169, June 8, 1965, Ser. No. 462,170, June 8, 1965, Ser. No. 462,183, June 8, 1965, Ser. No. 550,209, May 16, 1966, Ser. No. 607,748, Jan. 6, 1967, and Ser. No. 607,749, Jan. 6, 1967. This application Jan. 18, 1968, Ser. No. 698,802

Int. Cl. D04h 3/08; D06c N06 US. Cl. 161-72 75 Claims ABSTRACT OF THE DISCLOSURE A wide variety of textile-like nonwoven fabrics is produced by traversing fibrous material with high energy liquid streams while supported on an apertured member, such as a perforated plate or woven wire screen, to consolidate the material in a repeating pattern of entangled fiber regions and interconnecting fibers. Fibers are randomly entangled in a manner which holds the fibers of the fabric in place without the need for bonding agents. Processes and apparatus are illustrated for preparing a loose layer of fibers and treating the layer with liquid jetted at a pressure of at least 200 p.s.i.g. from a row of small orifices to convert the layer directly into coherent, highly stable, strong nonwoven fabrics which resemble many textile fabrics prepared by conventional process steps such as mechanical spinning and weaving.

CROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation-in-part of my applications Ser. No. 299,805 filed Aug. 5, 1963, Ser. No. 391,641 filed Aug. 24, 1964, Ser. No. 442,251 filed Mar. 24, 1965, Ser. No. 462,169 filed June 8, 1965, Ser. No. 462,170 filed June 8, 1965, Ser. No. 462,183 filed June 8, 1965, Ser. No. 550,209 filed May 16, 1966, Ser. No. 607,749 filed Jan. 6, 1967, all now abandoned, and Ser. No. 607,748 filed Jan. 6, 1967.

BACKGROUND OF THE INVENTION This invention relates to a new jet process and apparatus for producing nonwoven fabrics, and to the novel fibrous products which are obtained. More particularly, it relates to patterned nonwoven structures and to process and apparatus for producing them by subjecting bulk fibrous materials to the action of high-energy-flux liquid streams.

Foraminous nonwoven webs have been made in the past by a variety of processes. For example, staple or papermaking fibers have been deposited from a slurry or from an air stream onto slotted forming screens or molds or onto screens having spaced protuberances in order to form webs, in which the fibers are arranged in groups in accordance with the pattern of the forming screen. Apertured webs have also been made by subjecting staple fiber webs to a localized mechanical working, for example, by perforating an unwoven sheet at spaced intervals with pins or by passing a wetted web between meshing toothed cylinders and using vibration to forcibly move segments of fibers apart to form holes in the web. Localized streams of gas or liquid have also been used to blow the fibers out of discrete areas of a web to thereby create a plurality of holes in the web. Foraminous nonwoven webs have also been produced by using ice dispersed low impact-pressure sprays of water to exert a washing action on the fibers of a staple fiber web, as the web is held sandwiched between an apertured plate and a fine mesh screen.

0f the above, those processes which require the use of vibrating needles, blowing and the like, in general, pro vide foraminous webs having a poorly ordered pattern and apertures which are irregular in size and shape. Formainous webs having a predetermined pattern and more uniform apertures may be achieved by the use of the air or slurry-deposition processes or by the spraywashing process described above. However, all of the above prior art procedures yield foraminous webs which have little or no integral strength. This lack of strength and coherence is due to the fact that the individual fibers within the web are not permanently associated with one another, with the result that the web can be readily pulled apart when subjected to stress. Some degree of strength and coherency may be imparted to such webs by the use of an adhesive or binder to bond the individual fibers together. The strength which can be achieved by such methods and the utility of the webs obtained are limited by the bonding power of the adhesive employed and its ability to retain its bonding power after repeated use and/or laundering of the web. Moreover, in many applications, the persence of any adhesive substance is undesirable, particularly when used in the amount required to develop some degree of strength, because of the deleterious effect of the adhesive on dyeability, drapability, hand and other properties important for textile uses. Finally, the additional cost of the binder and of its application to the web add to the overall cost of the product.

SUMMARY OF THE INVENTION The present invention provides for the production of textile-like nonwoven fabrics of fibers randomly entangled with each other in a repeating pattern of localized entangled regions interconnected by fibers extending between adjacent entangled regions. This invention also provides a process for consolidating fibers or filaments into strong patterned structures without using the conventional process steps previously required for producing strong, nonbonded, patterned fabrics, such as weaving, knitting, netting or the like, and without the need for binder or other supplementary treatment. The present invention further provides apparatus for the direct conversion of bulk fibrous materials into such patterned nonwoven fabrics. The present invention also provides for such production of textile-like nonwoven fabrics from a wide variety of types and lengths of fibers, starting with various forms of bulk fibrous materials, an important improvement over conventional weaving or knitting with yarns of staple fibers which are formed into yarn by drafting and twisting operations and must be of suitable length. The present invention also provides a multitude of new and useful patterned nonwoven fabric products. These and other advantages of this invention will become apparent in the course of the following specification and claims.

The novel products of the present invention are textilelike nonwoven fabrics comprising fibers locked into place by fiber interaction to provide a strong cohesive structure without the need for binder or filament fusing. The products have a repeating pattern of entangled fiber regions, of higher area density (Weight per unit area) than the average area density of the fabric, and interconnecting fibers which extend between the dense entangled regions and are randomly entangled with each other in the dense entangled regions. Many different patterns can be provided as disclosed subsequently. Localized entangled regions may be interconnected by fibers extending between adjacent entangled regions to define regions of lower area density than that of tthe adjacent fabric. A pattern of apertures substantially free from fibers may be defined by the dense entangled regions and interconnecting fibers. In preferred products the dense entangled regions are arranged in a regular pattern and joined by ordered groups of fibers to provide a fabric having an appearance similar to that of a conventional woven fabric, but in which the fibers proceed randomly through the fabric from entangled region to entangled region. The fibers of an ordered group may be either substantially parallel or randomly disposed relative to one another. Embodiments include fabrics having complex fiber structures with entangled fiber regions interconnected by ordered fiber groups located in different thickness Zones of the fabric, which are particularly suitable for apparel, including dress goods and suiting materials.

As stated, fibers are locked into place in the fabric by fiber interaction. By locked into place is meant that individual fibers of the structure not only have no tendency to move from their respective positions in the pat- H terned structure but are actually physically restrained from such movement by interaction with themselves and/ or with other fibers of the fabric. Fibers are locked into place in the entangled fiber regions of higher area density than the average area density of the fabric, and such fiber interaction may also occur elsewhere.

By interaction" is meant that the fibers turn, wind, twist back-and-forth, and pass about one another in all directions of the structure in such an intricate entanglement that they interlock with one another when the fabric is subjected to stress. This can be measured by the fiberinterlock test described near the end of the specification. The fabrics of this invention have a fiber-interlock value due to fiber entanglement of at least 7. Fabric bonded with binder will give higher values than the same fabric before bonding. Since the value determined in the absence of binder is at least 7 for the products of this invention, it is desirable to test samples before bonding or after substantial removal of any binder present, if this is possible. For nonbonded fabrics, the proportion of fibers which have interlocking entanglement can be evaluated by the evaluated by the entanglement completeness test described near the end of the specification, and the average intensity of fiber entanglement along the fibers can be estimated by the entanglement frequency test. In preferred products, the fiber entanglement frequency for nonbonded fabric is at least per inch with a fiber entanglement completeness of at least 0.5. Fabrics having entanglement frequencies of at least 40 per inch are also provided for uses requiring outstanding surface stability.

The three-dimensional character of the fiber entanglement described above is readily seen when fabric crosssections through entangled regions are observed at high magnification with a microscope having sufficient depth of focus, and can be evaluated in various ways, e.g., by the relatively simple internal-bond test described at the end of the specification. Included within the scope of the invention are textile-like nonwoven fabrics of fibers locked into place in a structure characterized by an internal-bond value of at least 0.2 foot-pound.

The entangled fiber structure is preferably characterized by random fiber segments that penetrate entangled fiber regions of the fabric and have a re-entrant loop configuration in the fiber segment which binds other fibers in place in the fabric. This is illustrated in FIGURE 36. By re-entrant loop configuration which binds other fibers in place" is meant the configuration of fiber segments (portions of a fiber) in the entangled region which emerge into view from random locations within the body of the fabric, are bent around and pass over other fibers, and then reenter the body of the fabric. A considerable fraction (generally a large fraction for fabrics having relatively large entangled areas) of these fiber segments normally emerge from and re-enter the same entangled region at a substantial angle to the fabric plane. The configuration of the re-entrant segment may resemble a hairpin or reflex loop (in the case where the emerging and re-entering legs are close together) and cause fibers to be bound in place in an analogous manner. The legs of such a reflex loop often penetrate entirely through the fabric to emerge from the opposite side of the fabric as either fiber ends or closed loops and, in some cases, may re-enter the fabric as second loops.

Fiber segments that penetrate entangled regions, and bind other fibers in place by a re-entrant loop configuration, are to a considerable degree responsible for the high level of fiber-interlock value characteristic of many products of this invention, since this structural feature distributed on the surface and through the volume of the fabric serves to generate an arrangement of fibers in the entangled regions with the latent ability to inter-lock, ensnarl, and tighten up when the fabric is deformed. This feature is in large part also responsible for the integrity leading to surface durability, wash resistance and coherence of these fabrics.

The re-entrant loop configuration of fibers as described above is most readily observed by coating the fibers on the faces of a fabric specimen with metal by a vacuum vaporization technique and photographing at high magnification with a microscope having a great depth of focus, preferably a scanning electrode microscope.

The entangled fiber regions of higher area density than the average area density of the fabric can be of any shape or size. An entangled fiber region can be quite long in one direction, or can have a compact shape for which the diameter of the inscribed circle is at least 50% of the diameter of a circle circumscribed about the perimeter of the region. Regions of fiber entanglement can extend substantially continuously along straight or sinuous paths, or can be distinct entangled fiber masses of essentially circular, square or oblong appearance. They may be interconnected by ordered fiber groups to define a pattern of apertures. By aperture is meant a hole in the fabric which may be completely free of fibers or contain relatively few stray fibers. The ordered fiber groups may hold the dense entangled fiber regions so closely together that apertures are not visible unless the fabric is stretched and/or observed with magnification. The term ordered applies to the gross appearance of fiber groups. The groups may be bundles or bands of yarn-like or ribbon-like appearance. The individual fibers may be substantially parallel, or become so when the fabric is stressed, or the fibers may be randomly entangled or otherwise disposed in arrangements capable of acting in concert to distribute fabric stress.

The repeating pattern of fiber arrangements can be regular, i.e., substantially identical arrangements are repeated periodically in one or more directions in the plane of the fabric, or the repeating pattern can be irregular. Most of the examples of this application are concerned with regular repeating patterns, but irregular or random patterns can be made as discussed subsequently. Depending on the fineness of the pattern produced on the patterning memher, or following such aftentreatments as shrinkage, development of fiber crimp or the like, the fiber arrangements forming the pattern may or may not be readily apparent upon visual inspection with the naked eye. However, they will be readily discernible with magnification. When viewed with transmitted light, the high density entangled regions will be revealed as dark areas in the fabric. With shrunk or crimped fibers, placing a slight strain on the fabric Will help to distinguish between dense entangled regions and ordered fiber groups.

The process of the present invention involves supporting a layer of fibrous material on an apertured patterning member for treatment, jetting liquid supplied at pressures of at least 200 pounds per square inch gage (p.s.i.g.) to form streams having over 23,000 energy flux in foot poundals/inch second at the treatment distance, and traversing the supported layer of fibrous material with the streams to entangle fibers in a pattern determined by the supporting member, using a sufficient amount of treatment to produce a uniformly patterned fabric. The terms apertured patterning member, energy flux and amount of treatment, and preferred apparatus for the treatment, will be explained in detail hereinafter.

As illustrated subsequently, the process can be used to produce a large number of different products by varying the initial material and/or the patterning member used. The initial material may consist of any web, mat, batt or the like of loose fibers disposed in random relationship with one another or in any degree of alignment. The term fiber" as employed herein is meant to include all types of fibrou materials, whether naturally or synthetically produced, comprises fibrids, paper fibers, textile staple fibers and continuous filaments. Improved properties can be obtained by suitable combinations of short and long fibers. Reinforced fabrics are provided by combinations of staple length fibers with substantially continuous fibrous strands, where the term strands includes continuous filaments and various forms of conventional yarns. Desirable products are produced from conventional textile fibers, which may be straight or crimped, and other desirable products are obtained by using highly crimped and/ or elastic fibers in the inital material. Particularly desirable patterned, nonwoven fabrics are prepared by using an initial material comprising fibers having a latent ability to elongate, crimp, shrink, or otherwise change in length, and subsequently treating the patterned, nonwoven structure to develop the latent properties of the fibers so as to alter the free-length of the fibers. The initial material may contain different types of fibers, e.g., shrinkable and nonshrinkable fibers, to obtain special effects upon activation of the latent properties of one type of fiber.

The term apertured patterning member includes any screen, perforated or grooved plate, or the like, on which the inital material is supported during processing and which by reason of its apertures and/or surface contours influences the movement of the fibers into a pattern in response to jets of high-energy-fiux liquid streams. The patterning member may have a planar or nonplanar surface or a combination of planar and nonplanar areas.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying photographs illustrate some of the many varieties of patterned, nonwoven fabric structures which may be made, their pattern depending on the selection of the apertured patterning member.

In accompanying illustrations of the invention,

FIGURE 1 shows a schematic view of one type of apparatus for carrying out the process of this invention.

FIGURE 2 is a schematic isometric view of an apparatus for the high-speed, continuous production of patterned nonwoven fabric.

FIGURE 3 is a photomicrograph in plan view of a portion of a patterned, nonwoven fabric prepared from filaments which have been highly crimped following production of the fabric, as described in Example 16. Magnification is the same as in FIGURE 4.

FIGURE 4 is a corresponding photomicrograph of the fabric of FIGURE 3 held under a multiaxial stress sufficient to elongate the fabric 15%. Magnification is indicated by the scale below the figure.

FIGURE 5 is an enlarged plan view of a portion of a patterning plate, showing the staggered arrangement of apertures used when the triangular-mesh, tanglelaced fabric of FIGURE 3 is prepared.

FIGURE 6 is a photomicrograph in plan view of a portion of the triangular-mesh sample of Example 17. Magnification is indicated by the scale at the side of the figure.

FIGURE 7 is a photograph of the fabric of FIGURE 6 after being subjected to the grab tensile test.

FIGURE 8 is like FIGURE 6 but illustrates the better appearance obtained in Example 30. Magnification is indicated by the scale beneath the figure.

FIGURE 9 is a photomicrograph of the square-mesh sample of Example 17 (at the magnification indicated by the scale beneath the figure).

FIGURE 10 is a photomicrograph showing the oblongshaped entangled regions in the product of Example 59.

FIGURE 11 is a photomicrograph in plan view of the square-mesh, nonwoven fabric of Example 10. Magnification is indicated by the scale beneath the figure.

FIGURE 12 is a similarly enlarged plan view of a portion of the plain weave patterning screen used to prepare the square mesh fabric shown in FIGURE 11.

FIGURE 13 is a photomicrograph of a different type of square-mesh, nonwoven fabrics, like the product of Example 42D but of lighter weight. Magnification is iniicated by the scale beneath the figure.

FIGURE 14 is a photomicrograph showing, with a product in the position formed, the type of patterning screen used to prepare the product of FIGURE 13.

FIGURES 15 and 15a are photomicrographs of the upstream and downstream (screen) faces of the product of Example 40C; FIGURES 16 and 16a are of the product of Example 40E; and FIGURES 17 and 17a are of the product of Example 40L. The products are shown as removed from the screens without further treatment, at the magnification indicated by the scales.

FIGURE 18 illustrates the general appearance of products of the above type when viewed without magnification.

FIGURE 19 shows details of the structural pattern in fabric prepared as described in Example 63(a). Magnification is indicated by the scale.

FIGURES 20-23 are enlarged views of patterning screens dscribed in Examples 45 and 47.

FIGURES 24 and 25 show upstream faces of products prepared as described in Example 45, and FIGURES 24a and 25a show the corresponding downstream faces. Magnification is shown by the scale beneath FIGURE 25.

FIGURES 26 and 27 are schematic illustrations of the structural pattern found in products of the above type.

FIGURES 28 and 28a are of the upstream and downstream faces of a product prepared as described in Example 45, showing the appearance when viewed without magnification.

FIGURES 29 and 30 show upstream faces of products prepared as described in Example 47, and FIG- URES 29a and 30a show the corresponding downstream faces. Magnification is shown by the scale.

FIGURES 31 and 31a show the normal appearance of the two faces of fabric produced as described in Example 47(E), and FIGURES 32-34 show the structural pattern at the magnification indicated by the scale; in FIGURE 32 (upstream face) and FIGURE 34 (downstream face) the fabric is viewed with direct illumination, and in FIGURE 33 the view is with light transmitted through the fabrics.

FIGURES 35 and 36 are greatly enlarged views of fiber entanglement in a fabric prepared as described in Example 63(B). Magnifications are indicated by the scales.

FIGURE 37 is a view of fiber entanglement in a fabric prepared as described in Example 29. Magnification is indicated by the scale beside the figure.

FIGURE 38 is a side-sectional view of a machine for air-laydown of fibers to form a random web suitable for treatment to form nonwoven fabrics.

FIGURE 39 is a side-sectional view of a card machine suitable for preliminary processing of fibers for preparing a web.

FIGURE 40 is a schematic side view of apparatus for continuously feeding and opening staple fibers, forming a web and jet treating the web to form patterned nonwoven fabrics. 

